| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is difficult [to-vb] | 1523 |
|
| 2 | it is difficult for | 139 |
|
| 3 | is difficult [to-vb] for | 16 |
|
| 4 | it is [to-vb] for | 11 |
|
| 5 | it difficult [to-vb] for | 8 |
|
